Dash AC blows out of the defrost vents
the dash AC blows out of the defrost vents when engine is under a strain, such as climbing up a hill, etc. my motor home is a 2000 itasca suncruiser. the engine is a ford v10 i feel it is a vacuum...
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Yes, its a vacuum leak. Have a look under the hood for a vacuum reservoir. Test it for leakage. You will need a vacuum pump for testing. Also have a look at any vacuum lines for cracking etc. You may have a vacuum check valve near the reservoir. Test it as well, when they get worn, they don't hold vacuum well.
